Re: [Bloat] dslreports bufferbloat tests

[Jonathan Morton <chromatix99@gmail.com>]

> On 21 Apr, 2016, at 01:53, jb <justin@dslr.net> wrote:
> 
> So Is there anything different, or detectable, on the server side for
> such a fully congestion aware connection, but no congestion is
> encountered?

This would imply that your server was unable to saturate the connection.  You should be able to infer this case by comparing the measured throughput to your server’s capacity.

> So on upload phase, I can see CE marks come in, but during download
> phase there is nothing interesting to detect and log?

Since the router handling the queue for the bottleneck link will likely be different in each direction (in the simple case, one is at the ISP and the other is in the subscriber’s home), it’s entirely possible for one direction to be fully ECN-aware and AQMed at the bottleneck, and the other to be completely bloated.  In both cases, the traffic will negotiate ECN (or not) the same way.

Additionally, even if there are ECN-aware, AQMed queues on the path, it’s the bottleneck queue that counts.  It’s possible to get some sporadic CE marks on a path where the major bottleneck link is bloated, if the traffic passes through an ECN-aware pinch point which is transiently congested.

 - Jonathan Morton